IN ADDITION TO THE USE OF POLAROGRAPHIC/VOLTAMMETRIC SYSTEMS FOR THE DETECTION OF OXYGEN AND/OR NITRIC OXIDE FROM SINGLE CELLS WE ARE EXPLORING THE POSSIBILITY OF USING THIS APPROACH FOR THE MEASUREMENT OF PHYSIOLOGICALLY RELEVANT METALS AND TOXIC HEAVY METALS. THE TECHNIQUE IS BASED ON DISCRIMINANTING ION FLUXES BY VIRTUE OF CLOSE REDOX POTENTIALS. HEAVY METALS ARE WIDELY SEPARATED WHEREAS PHYSIOLOGICAL METAL IONS ARE TIGHTLY GROUPED. WE ARE CONFIDENT THAT THE FORMER CAN BE MEASURED AT THE SINGLE CELL LEVEL. DETECTING AND DISCRIMINATING THE LATTER WILL UNDOUBTEDLY BE A GREATER CHALLENGE.